1. Field of the Invention
The present invention generally relates to radiative energy, and in particular it relates to an X-ray Talbot interferometer and an X-ray imaging system equipped with a Talbot interferometer.
2. Description of the Related Art
Recently, an image capturing method called X-ray phase contrast imaging has been studied in which contrast is generated on the basis of a phase change of X-rays caused by the X-rays passing through an inspection object. As an example of X-ray phase contrast imaging, an image capturing method called X-ray Talbot interferometry using Talbot interference has been described in International Publication No. WO04/058070.
An overview of a Talbot interference method will be described. In a Talbot interference method, an X-ray Talbot interferometer is generally used that includes a diffraction grating, a shield grating, and a detector configured to detect X-rays from the shield grating. When the diffraction grating is irradiated with spatially high coherence X-rays, such X-rays are diffracted by the diffraction grating and form an interference pattern (which may also be called a self-image) that has a brightness period at specific positions (the Talbot effect). Generally, the period of this self-image is smaller than the size of pixels of the detector. Thus, a portion of the self-image is blocked by the shield grating, a periodic pattern with a wider pitch is formed, and this periodic pattern is detected by the detector.
When an inspection object is arranged between an X-ray source and the detector, X-rays from the X-ray source are refracted, absorbed, and scattered by the inspection object. As a result, the self-image is changed and a periodic pattern formed by the self-image and the shield grating is also changed. Information on the inspection object may be obtained by detecting this periodic pattern by using the detector and, if necessary, by performing calculation using a detection result.